//public class Base {
//    public int sum(int a,int b){
//        System.out.println("base_int_int");
//        return a+b;
//    }
//}
public class Base {
    public long sum(int a,long b){
        System.out.println("base_int_long");
        return a+b;
    }
    public boolean canCast(Base b){
        return b instanceof Child;
    }
}